Rheostat.



PATENTED SEPT. 1, 1903.

' E. WESTON.

RHEOSTAT. APPLICATION FILED JULY 9. 1902.

4 SHEETS-SHEET 1.

1T0 MODEL.

PATBNTED SEPT. 1,- 1-903.

E. WESTON. RHEOSTAT.

' APPLIOATION FILED JULY 9. 1902.

4 SHEETS-SHEET 2.

N0 MODEL.

PATENTED SEPT. 1. 1903.

E. WESTON. RHEOSTAT. urmoumu FILED JULY 9. 1902. no MODEL. 4 SHEETS-SHEET a.

ms: NORRIS PETERS cu. FHOTD-LITHO,WASHINGTCN, n c

No. 737,982; PATENTED SEPT. l, 1903.

WESTON.- RHEOSTAT.

APPLIGATION FILED, JULY 9' 1802.

' 4 SHEBTSSHEBT 4.

H0 MODEL.

W Illunnnv 'HIIIIIH I IIIIIIIIIIIIIH .1 will WWW mar TH: Moflms PETERS co, PHOTQLITHQ, WASHYNGTDN. n. c.

UNITED STATES 'i atented September 1, 1903.

PATENT ()EEIcE.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 737,982, dated September 1, 1903.

Application filedJuly 9, 1902- Serial No. 114,942. (No model.)

To utZZ whom it may concern:

Beitknowu thatI,EDWARD lVEsTON, a subject of the King of Great Britain, residing at Newark, in the county of Essex and State of New Jersey, have made a new and useful Invention in Rheostats, of which the following is a specification.

My invention is directed to improvements in rheostats designed particularly for use in connection with electrical currents of large quantity, and has an especial use in connection with the testing of electrical measuring instruments where wide variations of currentfiow are utilized; and it has for its objects, first, to devise a rheostat in which the variation of current-flow therethrough is effected by the application of liquid or gas pressure, whereby delicate regulation is accomplished; second, to devise a rheostat in which all of the parts shall be as compact and as stable as possible, so that there will be no liability of any substantial variation or change of the structure which would materially afi'ect its efficiency; third, to devise a rheostat in which the variations of current-flow through all of the individual current conducting parts thereof shall be effected simultaneously and under such conditions of usage as will avoid any material heating of the parts; fourth, to devise a rheostat in which the variations of currentflow through the individual parts thereof shall be effected by applying pressure between the surface areas of the current-conducting parts and in such manner that the pressure shall be substantially equal at all points; fifth, to devise a rheostat in which the variations of current-flow through the current-conducting parts thereof shall be effected by applying air or liquid pressure between said parts and in such manner that a wide and gradual variation of current-flow may be effected with the desired nicety of adjustment.

My invention will be fully understood by referring to the accompanying drawings, in which- Figure l is a side elevational View of the entire instrument, and Fig. 2 is a plan View thereof as seen looking at Fig. 1 from the top toward the bottom of the drawings. Fig. 3 is an end elevational view as seen looking at Figs. 1 and 2 from right to left. Fig. 4 is an edge view of the same part as seen looking at Fig. 8 from the top toward the bottom of the drawings.

In the manufacture and calibration of electrical measuring instruments, particularly electrical-current ainmeters where large Variations of current-floware often necessitated it is especially important that the currentfiow through the instrument to be calibrated be subjected to minimum variations due to the heating of the exterior circuit through which it is transmitted. My present invention is designed especially for such use; and

to this end it consists in combining in a rheostat two sets of condnoting-electrodes,preferably of metal, with carbon or other conducting material and in confining between said sets of electrodes expansible means for varyingthe pressure between the two sets of electrodes and the carbon or like material and in such manner that the variations of the current-flow through all parts of the rheostat shall be substantially alike and without any detrimental effects due to abnormal heating.

For a full and clear understanding of my invention, such as will enable others skilled in the art to construct and use the same, reference is had to the accompanying drawings and first to Figs. 1 and 2.

2 2 represent metallic standards or supports, to which are secured at their upper ends by screws 3 3 3 two webbed metal end plates 1 1 of great strength.

7 7 are blocks of insulating material secured to the upper end of the end plates 1 1 by bolts, as shown.

6 is one of the conducting-terminals, constructed, preferably, of a copper bar of large cross-section, being provided at its free end with a binding-plate 30 and binding-bolts for connecting the terminals to one pole of the source of electrical energy.

5 5 represent two similar conducting-terminals in the nature of copper bars each of large cross-section and secured by bolts directly to the end plates 1 1 on the opposite sides thereof and to copper spacing-blocks 1O 10, threaded upon the bolts 4 4 4 4, (see Fig. 6,) the free ends of said terminals being connected together by bolts, so as to constitute a binding-terminal 31, to which the other pole of the source of electrical energy is connected. The bolts 4 4 4 4 extend entirely through the body of the instrument and are secured at their opposite ends directly to the end plates by nuts, as shown.

11 11 are electrodes of rectangular-shaped sheets of metal, such as brass or copper, which are threaded loosely upon the bolts 4 4 and between the spacing-blocks 1O 10.

29 29 are rectangular-shaped bodies or sheets of carbon or other conducting mate= rial, whichrest against and are secured by screws to the opposite sides of the metallic electrodes 11 11.

15 15 are copper or equivalent metallic electrodes of disk-like form secured to thin flexible suspending-strips of conducting material 16 16, threaded upon bolts 8 8, extending the entire length of the frame and supported by the insulating-blocks 7 7, said strips being spaced from each other by conducting spacing-blocks 23, secured directly to the terminal 6 by pairs of screws, as shown. The

electrodes 15 15 are arranged in pairs between the inner or adjoining faces of the carbon plates, and each pair is provided with pairs oflaterally-extending arms 17 17, having facenotches 18 18, (see Fig. 9,) said arms being perforated for the purpose of receiving screws 20, extending into spacing sleeves or washers 21. (See Fig. 4.)

19 19 are leaf-springs which tend to draw the electrodes 15 15 toward each other.

12 12 are rectangular-shaped sheets of metal having large openings cut therethrough, and 22 22 are corrugated diaphragms secured directly to the sheets 12 and on opposite sides thereof by metallic rings and rivets, as clearly shown in Fig. 7 and as shown in cross-sectional view in Figs. 4 and 5, the arrangement being such that when these pairs of corrugated diaphragms are held together between the metallic electrodes 15 15 the latter through the action of the leaf-springs 19 19 maintain the corrugations normally in contact with each other in the several cells, said corrugated diaphragms when thus joined together and to the sheet-metal plates 12 12 constituting, in effect, expansible air-tight cells or chambers adapted to be expanded under the influence of air injected therein through nipples 25 25 and flexible air-tubes 26 26, connected to a main air-pipe 27 by nipples 32 32, 28 being a main nipple forconnecting a source of air-supply to the pipe 27. These air cells or chambers are provided each with a pair of screw lugs or arms 13, extending upward through insulating-rods 9 9, of hard rubber or the like, resting upon the upper edges of the electrodes 11 11, 14 being thumb-nuts for securing said parts in position.

24 24 are pairs of spacing-lugs located on opposite faces of the metal plates 12 for spacing the difference between them and the inner faces of the metallic electrodes 15.

When the different parts of the instrument are assembled, the spacing-blocks 23 and the suspending-strips 16 are bound together in a firm contact with each other by the bolts 8 and inner pairs of nuts at the opposite ends thereof, and the outer ends of the bolts are secured in place in the insulating-blocks 7 7, so as to support the electrodes 15 15 in the manner shown and described. In like manner the carbon-plates 29 29 and the metallic electrodes 11 11 and spacing-blocks 10 are bound together in such manner as to support all of the parts in an absolutely-rigid condition, the entire structure being of such a compact nature, as is obvious on inspection of the drawings, that by reason of the stability of the parts there is little prospect of any change of location or structural variation of any of the parts. When the instrument is ready for use, an air-supply (not shown) is connected with the nipple 28, and air is admitted to the air-pipe 27 through the branch air-pipes 26 26 to the air cells or chambers at such pressure as will cause the diaphragms 22 to expand and to force outward in opposite directions the electrodes 15 15 against the normal action of the pairs of leafsprings 19 19. By virtue of this expansion and the variable surface pressure of the electrodes 15 15 upon the carbon resistances 29 29 variation in current-flow is effected in a manner well understood by those skilled in the electrical art, it being apparent that by reason of the compactand stable nature of all of the parts of the instrument a Variation in currentflow may be effectedwithin wide ranges, and this by successive steps without danger of damage to the instrument itself or without any undue heating at any structural part thereof.

I do not limit my invention to the especial details of construction hereinbefore described, and shown in the accompanying drawings. I believe it is broadly new with me to devise a rheostat in which the Variation of currentflow therethrough is effected by a variation of pressure applied between adjoining sets of electrodes, and my claims are generic as to this feature. Ibelieve it is also broadly new with me to effect the variation of resistance in a rheostat by the application of a liquid or fluid source of energy under pressure between the electrodes, and my claims are generic as to this feature, it being obvious that instead of utilizing air I may utilize any other gas or water, oil, or any liquid adapted to fiow into and out of an expansible cell or chamber having one or more surfaces bearing on, against,

or between electrodes capable of varying the relation of current-flow by reason of such pressure, and my claims are also generic as to this feature.

Having thus described myinvention, what I claim, and desire to secure by Letters Patent of the United States,-is

1. A rheostat provided with a series of electrodes so constructed as to be varied in their conductivity by pressure; in combination with a liquid or gaseous medium under pressure and means for admitting the application of said liquid or gaseous medium against the electrodes in such manner as to vary the currentfiow therethrough.

2. A rheostat embracing two or more electrodes located side by side and capable of movement to or from each other; in combination with a liquid or gas under pressure and means for applying said liquid or gas against the electrodes in such manner as to vary the pressure between the same and correspondingly vary the current-flow therethrough.

3. A rheostat provided with conducting material and electrodes having surface-bearing against the same; in combination with expansible means located between said parts for varying the current-flow therethrough by variation of pressure, substantially as described.

4. A rheostat embracing pairs of metallic electrodes and conducting-terminals connected thereto; in combination with conductingbodies located between said electrodes; together with expansible means intermediate said parts for varying the current-flow therethrough by pressure, substantially as described.

5. Arheostatembracingaseriesof conducting-plates and two series of metal electrodes intermediate the same; in combination with means located between said plates and electrodes for varying the current -flow there through by pressure, substantially as described.

6. A rheostat embracinga series of conducting-plates and two series of metal electrodes all supported in a rigid frame or casing; in combination with means located between said electrodes and plates for varying the currentflow therethrough by pressure, substantially as described.

7. A rheostat embracing two rigid end plates operatively connected together by bolts; in combination with two series of sheetlike electrodes and intermediate carbon plates, all held in place between said end plates; together with expansible air cells or chambers located between said parts and operatively connected to a source of air-supply, the electrodes being connected to the terminals of the rheostat, substantially as described.

8. A rheostat embracing two rigid end plates held together by bolts; a series of condncti n g-plates, and two series of metallic electrodes all secured between the end plates; together with a series of eXpansible air cells or chambers located one between each pair of said electrodes and operatively connected to a source of air-supply, the pairs of metallic electrodes being connected to the terminals of the rheostat, substantially as described.

9. A rheostat embracing two series of metallic electrodes operatively connected to the terminals thereof and a series of conductingplates, alternately disposed with said electrodes; in combination with a series of expansible air cells or chambers located one between each pair of said electrodes and operatively connected with a source of air-supply, substantially as described.

10. A rheostat embracing two series of electrodes in the nature of sheets of metal operatively connected to the terminals thereof; in combination with a series of sheets of carbon; together with a series of expansible air cells or chambers located between said electrodes and the carbon-sheets and operatively connected with a source of air-supply, all of said electrodes being secured between two rigid end plates so connected together as to withstand great pressure, substantially as described.

11. A rheostat embracing two series of sheet-like electrodes and a series of sheets of carbon, all secured between two rigid end plates operatively connected together by means adapted to withstand great pressure; in combination with a series of expansible air cells or chambers composed of corrugated plates placed face to face between the electrodes and the carbon-sheets and operatively connected with a source of air-supply, one set of said electrodes being connected to one terminal of the rheostat and the other set to the other terminal thereof, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

EDWARD WESTON.

Witnesses:

WILLIAM H. YAWGER, ADELBERT O. BENEoKY. 

